Enrichment Of Lithium From Xinmin Bauxite In Northern Guizhou And Its Indication Of Lithium Isotope

Bauxite is the product of extreme weathering and an important carrier of Li.Because of the large amount of resources,the study on the enrichment mechanism and distribution of Li in bauxite will be beneficial to the prospecting prediction.Among the bauxite concentration areas in guizhou province,Wuzhengdao area have the highest Li content,and Xinmin bauxite deposit is a known typical representative.Based on the research results of Li isotope analysis,a Li isotope analysis scheme that can be applied to bauxite ore is proposed in this study,which provides scientific guidance for accurately tracing the source and process of trace matter and further revealing the metallogenic mechanism of rare metals in the mining area.In this study,Xinmin bauxite was comprehensively analyzed and rock samples from 5boreholes were collected.The petrology and mineralogy of 5 boreholes were analyzed find that?1?In general,the Li content of the earthy bauxite and semi-earthy bauxite ore section is low,and the Li content of the ore-bearing rock series has a gradually increasing trend from the bottom to the top;?2?There is no obvious change trend of Li content in the two directions of tendency and direction,and there is a phenomenon of local enrichment;?3?The thickness of the ore-bearing rock series formed when the underlying stratum is limestone of the C₂h is greater than that when the underlying stratum is the mud shale of the S_1-2hj,and the more ore composition types in the ore-bearing rock series,the Li content There is an increasing trend;?4?When the ore contains 1 to2 minerals,the lithium content is low.Lithium concentrates when the ore contains 3 to 6 minerals.Through geochemical analysis,the ore body and surrounding rock element performance is significantly different,Li,Sc,Ga associated elements in the ore body enrichment.The ratio of Cr/Ni,Zr/Ti and Nb/Ta comprehensively judges that the bauxite mineral source is relatively extensive,and Neoproterozoic-Mesoproterozoic magmatic rock may be the ultimate source;The Zr-Hf ratio indicates that the bauxite is closely related to the underlying mudstone of S_1-2hj;The correlation of Sr,Sr/Ba and V/Zr with Li indicates that bauxite is mainly formed in the transitional facies,and there are some land facies and marine faces,and the depositional environment of transitional facies and land facies are more conducive to the enrichment of lithium than the marine faces sedimentary environment;The correlation between Sr/Cu and Li indicates that Li is easy to enrich in warm and humid climate,but Li also has an abnormal enrichment trend in hot and dry climate.Combined with Li content and Li isotope analysis found that?1?Bauxite has relatively uniform isotopic composition??⁷Li=-2.12‰?+2.41‰?,while the?⁷Li value of the surrounding rock reflects the extreme weathering of the ore-bearing rock series in the study area while the?⁷Li of the surrounding rock has a wide range??⁷Li=-10.33‰?1.56‰?,which reflects the extreme weathering of the ore-bearing rock series in the study area;?2?Bauxite is the same as?⁷Li in the continental crust??⁷Li=0‰±2‰?,which indicates that the weathering process of ore-bearing rock series is extremely long;?3?In different types of bauxite,the?⁷Li value of the earthy bauxite and semi-earthy bauxite is lower than that of dense massive bauxite.During the formation of bauxite,although montmorillonite can adsorb ⁶Li,⁷Li does not produce isotope fractionation,but as the desiliconization and aluminum-rich is strengthened and the ability of the ore to resist leaching is weakened,⁷Li preferentially enters the water body,resulting in the?⁷Li value of the earthy bauxite and semi-earthy bauxite being lower than that of dense massive bauxite.